556012b7ee
main work by @drewhk with contributions from @2m and @rkuhn This work uncovered many well-hidden bugs in existing Stages, in particular StatefulStage. These were hidden by the behavior of OneBoundedInterpreter that normally behaves more orderly than it guarantees in general, especially with respect to the timeliness of delivery of upstream termination signals; the bugs were then that internal state was not flushed when onComplete arrived “too early”.
77 lines
2.2 KiB
Scala
77 lines
2.2 KiB
Scala
package docs.stream.cookbook
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import akka.stream.ClosedShape
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import akka.stream.scaladsl._
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import akka.stream.testkit._
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import akka.util.ByteString
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class RecipeKeepAlive extends RecipeSpec {
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"Recipe for injecting keepalive messages" must {
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"work" in {
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type Tick = Unit
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val tickPub = TestPublisher.probe[Tick]()
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val dataPub = TestPublisher.probe[ByteString]()
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val sub = TestSubscriber.manualProbe[ByteString]()
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val ticks = Source(tickPub)
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val dataStream = Source(dataPub)
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val keepaliveMessage = ByteString(11)
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val sink = Sink(sub)
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//#inject-keepalive
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val tickToKeepAlivePacket: Flow[Tick, ByteString, Unit] = Flow[Tick]
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.conflate(seed = (tick) => keepaliveMessage)((msg, newTick) => msg)
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val graph = RunnableGraph.fromGraph(FlowGraph.create() { implicit builder =>
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import FlowGraph.Implicits._
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val unfairMerge = builder.add(MergePreferred[ByteString](1))
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// If data is available then no keepalive is injected
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dataStream ~> unfairMerge.preferred
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ticks ~> tickToKeepAlivePacket ~> unfairMerge ~> sink
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ClosedShape
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})
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//#inject-keepalive
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graph.run()
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val subscription = sub.expectSubscription()
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// FIXME RK: remove (because I think this cannot deterministically be tested and it might also not do what it should anymore)
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tickPub.sendNext(())
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// pending data will overcome the keepalive
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dataPub.sendNext(ByteString(1))
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dataPub.sendNext(ByteString(2))
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dataPub.sendNext(ByteString(3))
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subscription.request(1)
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sub.expectNext(ByteString(1))
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subscription.request(2)
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sub.expectNext(ByteString(2))
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// This still gets through because there is some intrinsic fairness caused by the FIFO queue in the interpreter
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// Expecting here a preferred element also only worked true accident with the old Pump.
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sub.expectNext(keepaliveMessage)
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subscription.request(1)
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sub.expectNext(ByteString(3))
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subscription.request(1)
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tickPub.sendNext(())
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sub.expectNext(keepaliveMessage)
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dataPub.sendComplete()
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tickPub.sendComplete()
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sub.expectComplete()
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}
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}
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}
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